Unicorn init.d script with support for different rbenv gemsets

readme

First download unicorn file to /etc/init.d/unicorn and chmod +x.
Mkdir /etc/unicorn/

Create file for your application for example /etc/unicorn/my_app.conf

Script will guess all needed values, so you can only create empty file my_app.conf.

Default values ( "my_app" is taken from .conf file name WITHOUT .conf extension. ):

* RAILS_ROOT=/home/my_app/www/current ( capistrano directories ). 
* RAILS_ENV=production. 
* APP_USER=my_app ( used to run unicorn as that user )
* UNICORN unicorn_rails

Every variable can be overwritten in .conf file.

Script assumes unicorn config will be in RAILS_ROOT/config/unicorn/RAILS_ENV.rb 
( for example /home/my_app/www/current/config/unicorn/production.rb )

It should be used with capistrano deployment as some paths are made for 
its directory layout: "current" and "shared" dirs.

production.rb

# RAILS_ROOT/config/unicorn.rb
# Search for "# SET ME!" and replace these with your own settings!.

HOW_DEEP_WE_R_FROM_RAILS_ROOT = "../.."

# Set environment to development unless something else is specified
RAILS_ROOT = File.expand_path(HOW_DEEP_WE_R_FROM_RAILS_ROOT, File.dirname(__FILE__))
SHARED_PATH = File.expand_path('../shared', RAILS_ROOT)

ENV['BUNDLE_GEMFILE'] = File.expand_path("#{HOW_DEEP_WE_R_FROM_RAILS_ROOT}/Gemfile", File.dirname(__FILE__))
require 'bundler/setup'

pid_path = "#{RAILS_ROOT}/tmp/pids/unicorn.pid"
pid pid_path

# See http://unicorn.bogomips.org/Unicorn/Configurator.html for complete
# documentation.
worker_processes 2 # SET ME!

# listen on both a Unix domain socket and a TCP port,
# we use a shorter backlog for quicker failover when busy
listen "#{SHARED_PATH}/sockets/unicorn.socket", :backlog => 1024 # SET ME!

# Preload our app for more speed
preload_app true

GC.respond_to?(:copy_on_write_friendly=) and
  GC.copy_on_write_friendly = true

# nuke workers after 30 seconds instead of 60 seconds (the default)
timeout 60

# Help ensure your application will always spawn in the symlinked
# "current" directory that Capistrano sets up.
working_directory RAILS_ROOT

stderr_path "#{SHARED_PATH}/log/unicorn.stderr.log"
stdout_path "#{SHARED_PATH}/log/unicorn.stdout.log"

before_fork do |server, worker|
  # the following is highly recomended for Rails + "preload_app true"
  # as there's no need for the master process to hold a connection
  if defined?(ActiveRecord::Base)
    ActiveRecord::Base.connection.disconnect!
  end

  # Before forking, kill the master process that belongs to the .oldbin PID.
  # This enables 0 downtime deploys.
  old_pid = pid_path + ".oldbin"
  if File.exists?(old_pid) && server.pid != old_pid
    begin
      Process.kill("QUIT", File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      # someone else did our job for us
    end
  end
end

after_fork do |server, worker|
  # the following is *required* for Rails + "preload_app true",
  if defined?(ActiveRecord::Base)
    ActiveRecord::Base.establish_connection
  end

  # if preload_app is true, then you may also want to check and
  # restart any other shared sockets/descriptors such as Memcached,
  # and Redis. TokyoCabinet file handles are safe to reuse
  # between any number of forked children (assuming your kernel
  # correctly implements pread()/pwrite() system calls)
end

unicorn

#!/bin/bash

### BEGIN INIT INFO
# Provides:          unicorn
# Required-Start:    $local_fs $remote_fs $network $syslog
# Required-Stop:     $local_fs $remote_fs $network $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start the unicorns at boot
# Description:       Enable Rails applications with unicorn at boot time.
### END INIT INFO

# This is /etc/init.d/unicorn (without .sh)
# init.d script for single or multiple unicorn installations. Expects at least one .conf
# file in /etc/unicorn
#
# Modified by http://github.com/ganta
# based on modified version by http://github.com/zewelor
# which is based on:
#   http://gist.github.com/2623205 by http://github.com/zewelor
#   http://gist.github.com/504875  by http://github.com/jaygooby
#   http://gist.github.com/308216  by http://github.com/mguterl
#
## A sample /etc/unicorn/my_app.conf
##
## RAILS_ENV=production
## RAILS_ROOT=/var/apps/www/my_app/current
## UNICORN="/opt/rbenv/shims/unicorn_rails"
## APP_USER="www-data"
#
# This configures a unicorn master for your app at /opt/my_app/current running in
# production mode. It will read config/unicorn.rb for further set up.
#
# You should ensure different ports or sockets are set in each config/unicorn.rb if
# you are running more than one master concurrently.
#
# If you call this script without any config parameters, it will attempt to run the
# init command for all your unicorn configurations listed in /etc/unicorn/*.conf
#
# /etc/init.d/unicorn start # starts all unicorns
#
# If you specify a particular config, it will only operate on that one
#
# /etc/init.d/unicorn start my_app
RBENV_FILE_TO_SOURCE=/etc/profile.d/rbenv.sh

sig () {
    test -s "$PID" && kill -$1 `cat "$PID"`
}

oldsig () {
    test -s "$OLD_PID" && kill -$1 `cat "$OLD_PID"`
}

cmd () {
    case $1 in
        start)
            sig 0 && echo >&2 "Already running" && return 0
            eval $CMD
            echo "Starting"
            ;;
        stop)
            sig QUIT && echo "Stopping" && return 0
            echo >&2 "Not running"
            ;;
        force-stop)
            sig TERM && echo "Forcing a stop" && return 0
            echo >&2 "Not running"
            ;;
        restart|reload)
            sig USR2 && sleep 5 && oldsig QUIT && echo "Killing old master" `cat $OLD_PID` && return 0
            echo >&2 "Couldn't reload, starting '$CMD' instead"
            eval $CMD
            ;;
        upgrade)
            sig USR2 && echo Upgraded && return 0
            echo >&2 "Couldn't upgrade, starting '$CMD' instead"
            eval $CMD
            ;;
        rotate)
            sig USR1 && echo rotated logs OK && return 0
            echo >&2 "Couldn't rotate logs" && return 1
            ;;
        *)
            echo >&2 "Usage: $0 <start|stop|restart|upgrade|rotate|force-stop>"
            exit 1
            ;;
    esac
}

setup () {
    CONFIG=$1

    export APP_NAME=`basename $1 .conf`

    echo "Launching ${APP_NAME}"

    if [ -z $APP_USER ]; then
        if [ `getent passwd | awk -F: '{ print $1 }' | grep "^${APP_NAME}$" | wc -l` -eq 1 ]; then
            export APP_USER=$APP_NAME
        else
            echo "The is no user defined in ${CONFIG}, and the is no user in the system called ${APP_NAME}"
            return 1
        fi
    fi

    if [ -z $RAILS_ROOT ]; then
        if [ -d "/home/${APP_USER}/www/current" ]; then
            export RAILS_ROOT="/home/${APP_USER}/www/current"
        else
            echo "Rails root is not defined in ${CONFIG}"
            return 1
        fi
    fi

    if [ -z $RAILS_ENV ]; then
        export RAILS_ENV="production"
    fi

    # If unicorn binary was not defined in config
    if [ -z $UNICORN ]; then
        UNICORN="unicorn_rails"
    fi

    cd $RAILS_ROOT || return 1
    export PID=$RAILS_ROOT/tmp/pids/unicorn.pid
    export OLD_PID="$PID.oldbin"

    CMD="sudo -u ${APP_USER} $(rbenv which $UNICORN) -E ${RAILS_ENV} -c ${RAILS_ROOT}/config/unicorn.rb -D"
    return
}

# either run the start/stop/reload/etc command for every config under /etc/unicorn
# or just do it for a specific one

# $1 contains the start/stop/etc command
# $2 if it exists, should be the specific config we want to act on
source $RBENV_FILE_TO_SOURCE

if [ $2 ]; then
    . /etc/unicorn/$2.conf
    setup "/etc/unicorn/$2.conf"
    if [ $? -eq 1 ]; then
        exit 1
    fi
    cmd $1
else
    for CONFIG in /etc/unicorn/*.conf; do
        # clean variables from prev configs
        unset APP_USER
        unset RAILS_ROOT
        unset RAILS_ENV
        unset UNICORN

        # import the variables
        . $CONFIG
        setup $CONFIG
        if [ $? -eq 1 ]; then
            continue
        fi
        # run the start/stop/etc command
        cmd $1
    done
fi